Gemstones such as diamonds are traditionally graded based upon their appearance characteristics. For example, the following diamond qualities are typically included in standard grading reports: shape; weight (carat); clarity; color; fluorescence; and cut characteristics. In the context of gemstone analysis, “fluorescence” refers to the emission of visible light from a gemstone while exposed to ultraviolet (“UV”) radiation. The fluorescence of diamonds is usually graded using the following classifications: None; Faint; Medium; Strong; and Very Strong.
Traditionally, diamonds are graded by human inspectors who have been trained to identify and quantify the visible characteristics (with or without the aid of test equipment). Human inspectors grade the fluorescence of a diamond (and other gems) by illuminating the diamond with a controlled UV light source and observing the visible light emitted from the diamond. The human inspectors classify the diamond according to the intensity of the emitted visible light. In a diamond grading lab environment, technicians usually employ fluorescence reference “master stones” to improve consistency. Nevertheless, due to the inherently subjective nature of human fluorescence grading, some diamonds may be misclassified, especially if the appearance of a diamond is on the borderline between classifications. Furthermore, the same human grader may classify a diamond differently depending upon a number of factors such as: his or her level of fatigue; the environmental conditions; the size and/or cut of the diamond; the color of the fluorescence; the orientation of the observation; the instability of the light source; and the like.
The prior art includes a number of instruments designed to “automate” some of the gemstone grading processes by removing the human component. These instruments serve as a confirmation of the human grading process, and are not intended to completely replace the human grading procedure. The prior art, however, does not include an inexpensive, simple to operate, diamond fluorescence measuring device that is designed to electronically measure the fluorescence of a diamond by illuminating the diamond with a stable UV light source. In contrast, sophisticated and expensive fluorescence measuring equipment exists for other uses such as fluorescence spectrophotometry, x-ray, and microscopy applications—gemstone fluorescence grading does not require such sophisticated and expensive equipment.